RANK overexpression and an increase in the ratio of RANK-L to osteoprotegerin was observed in both PD and RA, with a high level of RANK-L expression on gingival B cells, most notably those capable of recognizing Pg. Infection with the virus worsens both periodontitis and RA, which act by promoting the growth of organisms such as Pg. Reciprocally, Pg could foster infection of oral keratinocytes by viruses such as EBV and CMV, as Pg OMVs promote the mucosal transmission of viruses. This evidence concerns the gene TNFRSF11A and rheumatoid arthritis.